Filling plugs through chemical mechanical polish

ABSTRACT

A scheme for filling plugs through chemical mechanical polishing comprises depositing a malleable conductive layer over a dielectric layer having openings formed therein. The malleable conductive layer is deposited such that a liner is formed within the openings, however the openings are not completely filled. A chemical mechanical polishing process using an alumina based slurry at a neutral or slightly basic pH and no oxidizer is used to smear the malleable conductive layer sufficiently to fill the remainder of the openings in the dielectric layer forming filled or substantially filled plugs.

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to the formation ofintegrated circuit devices and structures, and more specifically to atechnique for filling plugs through chemical mechanical polishing.

[0002] Silver and other malleable metals including gold, platinum, andcopper are considered important materials for manufacturing a variety ofintegrated circuits such as memory devices. For example, aluminum is acommonly used metal for forming devices and interconnects.

[0003] Unfortunately, there are a number of manufacturing obstaclesattributable to the use of such materials in integrated circuit devicefabrication. For example, one common processing technique, chemicalmechanical polishing (CMP), is commonly employed in integrated circuitdevice fabrication for polishing away conductive materials for formingplugs, interconnects and other devices. However, it is not uncommon forcertain malleable metals such as silver and silver-based materials toinadvertently pull from the plug during CMP processing. This isparticularly problematic when forming devices and interconnects wheresilver is intended to form a plug coupling to an underlying layer oftungsten. Silver adheres poorly to tungsten, thus the silver pullseasily from the plug. Even in cases where the metal does not completelypull from the via, inconsistent or otherwise unreliable structures suchas partially filled vias can result post CMP. This can lead to opencircuit connections or high resistance plugs.

[0004] Therefore, there is a continuing need for a CMP process inintegrated circuit device fabrication that allows consistent andreliable formation of devices and interconnects using malleable metals.

BRIEF SUMMARY OF THE INVENTION

[0005] This need is met by the present invention wherein a scheme forfilling plugs comprises depositing a malleable conductive layer over adielectric layer having openings formed therein. The malleableconductive layer is deposited such that a liner is formed within theopenings, however the openings are not completely filled. Achemical-mechanical polishing (CMP) process is then performed such thatthe malleable conductive layer smears, filling the openings and definingfilled or substantially filled plugs.

[0006] More specifically, a special chemical mechanical polishing (CMP)process is used to fill the remainder of the vias with the malleableconductive layer such that reliable devices and interconnects areformed. For example, when using a silver-based conductive material asthe malleable conductive layer, the silver-based conductive material ispolished by CMP using an alumina based slurry at a neutral or slightlybasic pH and no oxidizer. It is believed that at least a portion of thesilver-based conductive material smears sufficiently during the CMPprocess to fill the remainder of the vias, forming filled orsubstantially filled plugs. It will be appreciated that the slurrycomposition will vary depending upon the malleable metal used for theCMP.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0007] The following detailed description of the preferred embodimentsof the present invention can be best understood when read in conjunctionwith the following drawings, where like structure is indicated with likereference numerals and in which:

[0008] FIGS. 1A-1H depict cross-sectional illustrations of a process offorming a device using a malleable conductive metal according to oneembodiment of the present invention;

[0009] FIGS. 2A-2H depict cross-sectional illustrations of a process offorming interconnects according to one embodiment of the presentinvention; and,

[0010]FIG. 3 is a schematic illustration of a chemical mechanicalpolishing apparatus.

DETAILED DESCRIPTION

[0011] In the following detailed description of the preferredembodiments, reference is made to the accompanying drawings that form apart hereof, and in which is shown by way of illustration, and not byway of limitation, specific preferred embodiments in which the inventionmay be practiced. It is to be understood that other embodiments may beutilized and that logical, mechanical and electrical changes may be madewithout departing from the spirit and scope of the present invention.

[0012] It shall be observed that the process steps and structuresdescribed herein do not form a complete process flow for manufacturingintegrated circuits. The present invention can be practiced inconjunction with a variety of integrated circuit fabrication techniquescurrently used in the art. As such, commonly practiced process steps areincluded in the description herein only if those steps are necessary foran understanding of the present invention.

[0013] For the purposes of defining and describing the presentinvention, it is noted that a malleable conductive layer is anymalleable metal alone or in combination with any material, composition,or mixture of materials. The present invention is particularly suitablefor filling plugs using silver or a silver-based conductive materialincluding for example pure silver, a silver containing an alloy such ascopper or gold, silver coated copper particles, silver-based conductivematerials dispersed in an organic medium, etc. Additionally, the presentinvention is also suitable for filling plugs using other malleablemetals such as gold, platinum, and to a lesser degree, copper. However,results will vary depending upon the malleability of the metal or alloyused to fill the plug according to the present invention.

[0014] Further, as used herein, the formation of a layer or region“over” a substrate or other layer refers to formation above, or incontact with, a surface of the substrate or layer. For example, where itis noted or recited that an insulating layer is formed over a substrate,it is contemplated that intervening structural layers may optionally bepresent between the insulating layer and the substrate.

Formation of a Malleable Conductive Layer Device

[0015] With reference to FIG. 1A, the structure includes a base layer 10and a first layer 12 formed over the base layer 10. The base layer 10 isany previously processed substrate. For example, if the structure is acapacitor for use in a memory cell, the base layer 10 may comprise aconnection to a source drain region of a transistor. However, thepresent invention is not limited to such applications. Rather, thepresent invention is applicable to the formation of any device where itis desirable to fill a plug with a malleable conductive material. Assuch, the specifics of the base layer 10 are not explicitly illustrated.The first layer 12 comprises an electrode, formed preferably of amaterial such as tungsten or a tungsten based material. The first layer12 is deposited using techniques as are known in the art.

[0016] As illustrated in FIG. 1B, a second layer 14 comprises adielectric material. The second layer 14 is preferably silicone nitride,but may also comprise any dielectric material as is known in the art,for example, silicon dioxide (SiO₂) (doped or undoped), phosphosilicateglass (PSG), borophosphosilicate glass (BPSG), silicon oxynitride, alow-k material such as polyamide, any other suitable insulator material.The second layer 14 may also comprise any combination of materials. Forexample, the second layer 14 may comprise a layer of BPSG deposited overthe first layer 12, then a silicon nitride layer deposited over theBPSG. The second layer 14 may be deposited using techniques known in theart. For example, a laser plasma chemical vapor deposition process(LPCVD) may be used to deposit a layer of silicon nitride. Further, itis noted that a silicon nitride material may comprise a pure siliconnitride material or a silicon nitride material including additionalcomponents or impurities.

[0017] A portion of the second layer 14 is removed completely to defineopening or via 16 as illustrated in FIG. 1C. It shall be appreciatedthat any number of vias 16 may be formed as the specific applicationdictates. The via 16 extends completely through the second layer 14 andmay be formed as a trench, via, hole, plug, or other bore as are knownin the art. Further, any technique can be used to form the via 16. Forexample, a patterned photoresist is formed using high-resolutionphotolithography, the resist masks out portions of the second layer 14defining the location where the via 16 is to be formed. An etchingprocess then removes the second layer 14 in the area of the via 16.

[0018] As illustrated in FIG. 1D, a third layer 18 is provided over thesecond layer 14 and within the via 16 so as to merely line the via 16.The third layer should not fill the via 16 entirely. The third layer 18comprises a malleable conductive layer. The malleable conductive layermay be deposited using techniques as are known in the art including forexample, electroless, evaporation, or sputtering techniques.

[0019] As shown in FIG. 1E, portions of the third layer 18 above thesecond layer 14 are removed in such a fashion that the via 16 is filledby at least a portion of the third layer 18. The third layer 18 withinthe via 16 electrically couples to the first layer 12 (tungsten forexample). To accomplish filling the via 16 with the third layer 18, aCMP process is used to smear the third layer 18 such that at least aportion of the third layer 18 that lies over the second layer 14 issmeared or pushed into the via 16 to combine with the portion of thethird layer 18 that merely lines the via 16 as illustrated in FIG. 1E.

[0020] As used herein, the term “smear” refers to an act or processwhereby a partially filled, lined or, previously unfilled via, plug,trench, or like structure is filled or substantially filled lotsubsequent to the act or process. For example, during the CMP processaccording to one embodiment of the present invention, it is believedthat a portion of the malleable conductive layer (third layer 18 asshown) on the surface of the second layer 14 spreads, daubs, squeezes,or is otherwise moved or pushed into the via 16 to plug or fill theopening. It is believed that it is the malleability of the third layer18 that allows the smearing to effectively fill the plug. The is CMPprocess, including the composition of suitable slurries used tofacilitate the smearing process are described more thoroughly herein.

Programmable Conductor RAM (SCRAM) Devices

[0021] A PC RAM cell is a programmable conductor based upon a GermaniumSelenide glass, chalcogenide, into which relatively high levels ofSilver is dissolved. One flow suitable to form this cell is describedwith reference to FIGS. 1A-1I. A structure is formed as described abovewith reference to FIGS. 1A-1E, using a silver-based conductive materialas the malleable conductive layer, or third layer 18. Referring to FIG.1F, a portion of the third layer 18 is etched back forming a space 20.For example, the third layer 18 is etched back approximately half waywithin the opening. A fourth layer 22 is deposited over the third layer18, and optionally over the second layer 14 as illustrated in FIG. 1G.The fourth layer 22 comprises a chalcogenide, such as a combination ofselenium and germanium. For example, Ge₃Se₇ is deposited usingtechniques such as evaporation, sputtering, or other processes wellknown in the art. Portions of the fourth layer 22 are removed such thatthe only portion of the fourth layer 22 remaining fills the space 20above the third layer 18 as illustrated in FIG. 1H. The device is thensuitably heated, or exposed to ultra violet (UV) radiation such that thethird layer 18 dissolves into the chalcogenide, or fourth layer 22 toform a solid solution 24 as illustrated in FIG. 1I.

[0022] As illustrated herein, the Programmable Conductor Cell isconstructed by depositing a silver-based conductive material in a viasuch that the via is lined. The via is then smeared such that the via isfilled with the silver-based conductive material. The silver-basedconductive material is etched back such that the via is approximatelyhalf full. The Chalcogenide is then deposited, the structure ispolished, then exposed to heat or light to form the solution.

[0023] It will be observed that the above device is merely demonstrativeof the type of device that may be formed according to the presentinvention. The present invention, lining a via with a malleableconductive layer, then filling the via by smearing using a CMPtechnique, can be used to build any number of devices.

Formation of a Malleable Conductive Layer Interconnect

[0024] For the purposes of defining and describing this embodiment ofthe present invention, it is noted that an interconnect comprises anytype of conductive line connecting devices, bond pads, or other elementsto each other, within an integrated circuit structure, device, orassembly. Interconnects are also commonly referred to as plugs,contacts, vias, etc.

[0025] Moreover, one of the exemplary embodiments described hereinillustrate the present invention as applied to the formation ofinterconnects at specific levels of integrated circuit fabrication.However, the processing techniques of the present invention may also beapplied to formation of interconnects at various levels of metallizationwithin an integrated circuit fabrication process.

[0026] With reference to FIG. 2A, the structure 100 includes a baselayer 102 and a first layer 104 over the base layer 102. The base layer102 is any layer in which it is desirable to form an interconnectstructure thereover. For example, the base layer 102 may comprise asilicon wafer or other substrate such as gallium arsenide, aluminumoxide, glass, ceramic, or other similar substrate material. The baselayer 102 may also comprises an interconnect structure having conductivepaths. It shall be understood that the base layer 102 may be anypreviously processed substrate.

[0027] The first layer 104 comprises a dielectric material and serves asa first etch stop layer. For example, the first layer 104 is preferablysilicone nitride, but may also comprise silicon dioxide (SiO₂) (doped orundoped), phosphosilicate glass (PSG), borophosphosilicate glass (BSPG),silicon oxynitride, a low-k material such as polyamide, any othersuitable insulator material. Further, it is noted that a silicon nitridematerial may comprise a pure silicon nitride material or a siliconnitride material including additional components or impurities. Thefirst layer 104 may also comprise any combination of materials. Forexample, the first layer 104 may comprise a layer of BPSG deposited overthe base layer 102, then a silicon nitride layer deposited over the BPSGto define the etch stop layer. The first layer 104 may be depositedusing techniques known in the art. For example, a laser plasma chemicalvapor deposition process (LPCVD) may be used to deposit a layer ofsilicon nitride as is known in the art.

[0028] As shown in FIG. 2B, portions of the first layer 104 are removedcompletely to define openings 106 that expose contact regions within thebase layer 102. The openings 106 extend completely through the firstlayer 104 and may be formed as trenches, vias, holes, plugs, or otherbores as are known in the art. Any technique can be used to form theopenings 106 in the first layer 104. For example, a patternedphotoresist is formed using high-resolution photolithography, the resistmasks out portions of the first layer 104 defining the locations ofwhere the openings 106 are to be formed. An etching process then removesthe first layer 104 in the area of the openings 106.

[0029] Referring to FIG. 2C, a second layer 108 is deposited over thefirst layer 104. The second layer is a conformal metal layer arrangedsuch that the openings 106 as shown in FIG. 2B are filled by the secondlayer 108. The second layer 108 is any metal as known in the art, andcan include for example, tungsten, aluminum, aluminum alloy, titanium,titanium nitride, gold, copper, copper alloys, molybdenum, silver,polycrystalline silico (polysilicon) or a variety of other conductivemetals individually or in combination. Known filling operations areusually accomplished by depositing the second layer 108 onto the exposedsurface of the first layer 104 sufficiently thick enough to fill thoseportions of the first layer 104 which have been left unoccupied byprevious deposition and/or etching operations or masked depositionoperations. Depending upon the composition of the first and secondlayers 104, 108, optional barrier layers or adhesion layers (not shown)as are known in the art may be used so that the second layer 108 adheresto the first layer 104 and the base layer 102. Any method known in theart may be used to form the second layer. For example, common techniquesinclude Physical Vapor deposition (PVD), or anisotropic etching ofCVD-deposited tungsten and titanium nitride layers.

[0030] Referring to FIG. 2D, portions of the second layer 108 above thefirst layer 104 are removed such as by CMP or other polishing techniquesdefining first contact regions 110 within the first layer 104. It shallbe observed that the first contact regions 110 electrically couple thesecond layer 108 in the first contact region 110 to devices within thebase layer 102. For example, the first contact regions 110 may couple toa source/drain region or gate of a transistor, to a plate of acapacitor, or to another interconnect structure on the base layer 102(not shown in FIGS. 2A-2H).

[0031] As illustrated in FIG. 2E, a third layer 112 is formed over thefirst layer 104 and first contact regions 110. The third layer 112 canbe comprised of any suitable dielectric material such as those describedwith reference to the first layer 104, but preferably comprises siliconnitride.

[0032] As shown in FIG. 2F, vias 114 are formed in the third layer 112such that the vias 114 are substantially aligned over the first contactregions 110, exposing portions of the first contact regions 110.According to one embodiment of the present invention, it is preferableto construct relatively deep vias 114 within the third layer 112. Forexample, according to one embodiment of the present invention, asuitable third layer 112 comprises a layer of silicon nitride having athickness T of at least approximately 1000 Å. More preferably, the thirdlayer 112 should have a thickness T between approximately 1500 Å and2000 Å. Further, according to one embodiment of the present invention,the size S of the via 114 is preferably greater than approximately 0.25microns and more preferably approximately 0.5 microns. The vias 114 arecreated using techniques known in the art. For example, it may bepreferable to etch the vias to form a shape that is wider at the topthan at any other vertical location. For example, the vias 114 maycomprise truncated V or U shaped geometries (not shown). Any process forforming vias 114 may be used as is known in the art.

[0033] Referring to FIG. 2G, a fourth layer 116 is provided over thethird layer 112 and within the vias 114 so as to merely line the vias114. The fourth layer 116 should not fill the vias 114 entirely. Thefourth layer 116 comprises a malleable conductive layer. The malleableconductive layer may be deposited using techniques as are known in theart including for example, electroless, evaporation, or sputteringtechniques.

[0034] As shown in FIG. 2H, portions of the fourth layer 116 above thethird layer 112 are removed in such a fashion that the vias 114 arefilled by the fourth layer 116 defining second contact regions 118 asshown in FIG. 2H. The first contact regions 110 electrically couple torespective second contact regions 118 defining interconnects 120. Toaccomplish forming the second contact regions 118, a CMP process may beused to smear the fourth layer 116 such that at least a portion of thefourth layer 116 that overlies the third layer 112 smears or pushes intothe vias 114 to fill or substantially fill the remainder of the vias 114not already filled by the portion of the fourth layer 116 that alreadylines the vias 114.

Chemical Mechanical Polishing

[0035] A CMP apparatus 200 is schematically illustrated in FIG. 3. Apolishing table 202 having an upper surface 204 is coupled to a tableshaft 206. A polishing pad 208 is held to the upper surface 204 of thepolishing table 202. Rotation of the table shaft, for example in thedirection of the directional arrow 210, thus rotates the polishing pad208 via the polishing table 202. A wafer carrier 212 includes apolishing head 214 having a lower surface 216, and a shaft 218 coupledto the polishing head 214. The lower surface 216 of the polishing head214 is adapted for seating a substrate, such as the structures discussedherein with reference to FIGS. 1A-1I and 2A-2H. For example, thestructure 100 as discussed with reference to FIGS. 2A-2H is positionedin face-to-face relationship with the polishing pad 208. The shaft 218of wafer carrier 212 can be rotated or moved using known means. Forexample, the wafer carrier 212 may be moved vertically in according todirectional arrow 220. By moving the wafer carrier 212 downwardaccording to directional arrow 220, a downward force may be applied tothe wafer carrier 212 such that the structure 100 is pressed against thepolishing pad 208.

[0036] During the CMP process, fluids provide an adhesive force betweenthe structure 100 and polishing head 214 of the wafer carrier 212 suchthat the structure 100 is adhered to the polishing head 214 by way ofsurface-tension effects therebetween. Solution delivery tubes or pipes224 have an ejection outlet, or nozzle 226, positioned over thepolishing pad 208 to deliver various solutions to the polishing pad 208.It shall be appreciated that while shown with two solution deliverypipes 224 in FIG. 3, one or more solution delivery pipes 224 mayactually be required depending upon the composition of the slurry andother job requirements. As shown in FIG. 3, a slurry mixture 228comprising a slurry 230 and a diluting solution 232 are delivered to thepolishing pad 208.

[0037] During the CMP process, a surface of the structure being polishedis held against the polishing pad 208 while chemical mechanicalpolishing (CMP) slurry mixtures 228 are dispensed and applied to thepolishing pad 208. During the polishing procedure, the rotationalmovement of polishing pad 208 will cause the slurry mixture 228 to flowradially outward. Some of the slurry mixture 228 will flow off polishingpad 208 due to the centrifugal forces of the rotation. Accordingly, inorder to keep an adequate amount of slurry mixture 228 on the polishingpad 208 during polishing, the slurry mixture 228 is typically suppliedto polishing pad 208 continually during the CMP process. The flow rateof the slurry mixture 228 will vary depending upon the slurry used andvarious rotation speeds of the polishing table 202 and the polishinghead 214. For example, according to one embodiment of the presentinvention, the rotational speed of the polishing table 202 isapproximately between 30 and 50 revolutions per minute (rpm) and therotational speed of the polishing head 214 is approximately between 25and 50 rpm.

[0038] As used herein, diluting solution 232 refers to diluents used towash away material from the polishing pad 208. For example, the dilutingsolution 232 may comprise a liquid applied to the polishing pad 208arranged to clean the polishing pad 208. Alternatively, the dilutingsolution 232 may comprise a buffer solution, or alternatively, simply asolvent. A buffer solution refers to a known solution comprising both aweak acid and weak base and having the ability to absorb small additionsof acids and bases without giving rise to a significant change in the pHof the solution. A known solvent generally refers to a liquid capable ofdissolving or dispersing other substances; typically the substance ofgreatest proportion in a solution is deemed the solvent. However, insolutions that contain water, water is typically deemed the solvent.

[0039] CMP techniques for malleable metals such as silver are well knownin the art. CMP of silver can be done with practically all types ofslurries available including alumina with hydrogen peroxide or potassiumiodate, and silica with ammonia or TMAH. However, when polishing silverusing conventional CMP techniques, the silver tends to pull away fromvias due to poor adherence of the silver with the underlying contactregion. For example, with reference to the structures discussed herein,a silver, or a silver-based conductive material may be used to fill avia and form an electrical contact with tungsten. However, pooradherence of silver to tungsten is well known.

[0040] It is believed that the malleable conductive layer, such assilver, smears into the vias during the CMP process thus filling thevias as shown in FIGS. 1D-1E and 2G-2H. If the malleable conductivelayer fills the vias prior to CMP, a higher stress is exhibited at thecenter of the plug. This tends to pull the malleable conductive layerout of the via. This phenomenon is worsened where the malleableconductive layer exhibits poor adhesion with the underlying contactregion. Such as when filling silver vias formed over an underlyingcontact region of tungsten. However, selecting a slurry mixture 228according to the present invention allows the MP process to causesmearing, which results in more of the malleable conductive layer in theplug or via after CMP than post sputter.

[0041] The preferred slurry 230 for a silver-based conductive materialcomprises an alumina abrasive at a neutral or slightly basic pH with nooxidizer. For example, a suitable alumina abrasive has a 100 nanometer(nm) particle size. While the pH may vary depending upon otherparameters of the slurry 230, a preferable range comprises a pH betweenapproximately 6 and 9. That is, the pH may be slightly acidic toslightly basic. However, a neutral to slightly basic pH, approximatelybetween 7 and 8 for example, is even more preferable.

[0042] The CMP process should be carried out at a low down force toensure intact plugs. For example, according to one embodiment of thepresent invention, when using a CMP apparatus such as that schematicallyillustrated in FIG. 3, the force applied to the wafer carrier 212 in thedownward direction according to directional arrow 220 may be less thantwo foot pounds. More preferably, the down force may be applied betweenapproximately 0.5 foot pounds to 1.5 foot pounds.

[0043] It should be observed that changes to the above-described slurry230 may have profound results and yield unsatisfactory devices andinterconnects. For example, the addition of hydrogen peroxide slows theremoval rate and tends to pull the plugs. Further, the use of colloidalsilica with ammonia may result in empty plugs being formed.

[0044] With respect to the above-described slurry 230, a slurry mixture228 comprising one part slurry to approximately 10 parts of dilutingsolution 232 is preferable, however, the exact slurry mixture 228 mayvary depending upon the slurry 230 and the diluting solution 232 used.

[0045] Finally, the slurry should be highly selective to the dielectriclayer underlying the malleable conductive layer being smeared by the CMPprocess. For example, where a silver-based conductive material fills avia in a silicon nitride dielectric layer, the slurry should be highlyselective to silicon nitride, meaning that more material per unit oftime is removed of the silver-based conductive material than the siliconnitride. For example, alumina is a preferable component of the slurry230 because alumina does not attack silicon nitride in an aggressivemanner.

[0046] While the present invention may be practiced with any number ofmalleable metals, silver is a preferable metal due to certain electricalproperties. For example, when properly doped with a chalcogenide in avia, current threshold switching may be realized. This is a usefulstructure for example, in constructing PC RAM cells. Also, silver ismore thermally stable than other commonly used metals, thus makingsilver more resistant to oxidation. Additionally, electromigration isbelieved to be less of a problem with silver than with many othermetals. Further, certain malleable metals that can be used with thepresent invention including silver, have lower resistivity thanaluminum, which is currently the most common metal used to forminterconnects. Aluminum has a resistivity of about 2.7 μΩ-cm. Byutilizing lower resistivity metals such as silver (approximately 1.2-1.5μΩ-cm), copper (approximately 1.7-1.8 μΩ-cm), or gold (approximately2.3-2.4 μΩ-cm), devices with smaller cross-sectional areas can be formedwithout increasing the total resistance of the device over a comparablealuminum device. This allows more dense integrated devices andinterconnects.

[0047] Having described the invention in detail and by reference topreferred embodiments thereof, it will be apparent that modificationsand variations are possible without departing from the scope of theinvention defined in the appended claims. More specifically, althoughsome aspects of the present invention are identified herein as preferredor particularly advantageous, it is contemplated that the presentinvention is not necessarily limited to these preferred aspects of theinvention.

What is claimed is:
 1. A method of filling a plug comprising: forming adielectric layer; forming an opening through said dielectric layer;depositing a malleable conductive layer over a surface of saiddielectric layer such that said malleable conductive layer enters saidopening, said malleable conductive layer within said opening beinginsufficient in quantity to plug said opening; and, smearing saidmalleable conductive layer such that at least a portion of saidmalleable conductive layer plugs said opening.
 2. A method of filling aplug according to claim 1, wherein said malleable conductive layer issmeared by performing a chemical mechanical polishing operation suchthat said malleable conductive layer plugs said opening.
 3. A method offilling a plug according to claim 2, wherein said chemical mechanicalpolishing operation is performed with a slurry free from an oxidizer. 4.A method of filling a plug according to claim 2, wherein said chemicalmechanical polishing operation is performed with a slurry free fromhydrogen peroxide.
 5. A method of filling a plug according to claim2,wherein said chemical mechanical polishing operation is performed witha slurry comprising an alumina abrasive.
 6. A method of filling a plugaccording to claim 2, wherein said chemical mechanical polishingoperation is performed with a slurry at generally a neutral to slightlybasic pH.
 7. A method of filling a plug according to claim 2, whereinsaid chemical mechanical polishing operation is performed with a slurrycomprised of an alumina abrasive at neutral to slightly basic pH, andfree of an oxidizer.
 8. A method of filling a plug according to claim 7,wherein said chemical mechanical polishing operation is performed with aslurry mixture comprised of said slurry and a diluting solution mixed ata ratio of ten parts of said diluting solution to one part of saidslurry.
 9. A method of filling a plug according to claim 1, wherein saiddielectric layer is formed to be at least 1000 angstroms thick.
 10. Amethod of filling a plug according to claim 1, wherein said opening isformed having a diameter of at least 0.25 microns.
 11. A method offilling a plug according to claim 1, wherein said malleable conductivelayer is smeared so as to increase the amount of said malleableconductive layer in said opening.
 12. A method of filling a plugaccording to claim 1, wherein said malleable conductive layer isdeposited by forming a liner of malleable conductive material in saidopening.
 13. A method of filling a plug according to claim 1, whereinsaid malleable conductive layer comprises a silver-based conductivematerial.
 14. A method of filling a plug comprising: forming adielectric layer; forming an opening through said dielectric layer;depositing a malleable conductive layer over a surface of saiddielectric layer such that said malleable conductive layer enters saidopening, said malleable conductive layer within said opening beinginsufficient in quantity to plug said opening; and, smearing saidmalleable conductive layer across said surface of said dielectric layersuch that at least a portion of said malleable conductive layer movesfrom said surface into said opening to plug said opening.
 15. A methodof filling a plug according to claim 14, wherein said malleableconductive layer is smeared by performing a chemical mechanicalpolishing operation such that said malleable conductive layer plugs saidopening.
 16. A method of filling a plug according to claim 14, whereinsaid chemical mechanical polishing operation is performed with a slurryat generally a neutral to slightly basic pH.
 17. A method of filling aplug according to claim 14, wherein said chemical mechanical polishingoperation is performed with a slurry comprised of an alumina abrasive atneutral to slightly basic pH, and free of an oxidizer.
 18. A method offilling a plug according to claim 14, wherein said dielectric layer isformed to be at least 1000 angstroms thick.
 19. A method of filling aplug according to claim 14, wherein said malleable conductive layercomprises a silver-based conductive material.
 20. A method of filling aplug comprising: forming a dielectric layer; forming an opening throughsaid dielectric layer; depositing a malleable conductive layer over asurface of said dielectric layer such that said malleable conductivelayer enters said opening, said malleable conductive layer within saidopening being insufficient in quantity to plug said opening; and,performing a chemical mechanical polishing operation such that at leasta portion of said malleable conductive layer plugs said opening.
 21. Amethod of filling a plug according to claim 20, wherein said chemicalmechanical polishing operation is performed with a slurry comprised ofan alumina abrasive at neutral to slightly basic pH, and free of anoxidizer.
 22. A method of filling a plug according to claim 21, whereinsaid chemical mechanical polishing operation is performed with a slurrymixture comprised of said slurry and a diluting solution mixed at aratio of ten parts of said diluting solution to one part of said slurry.23. A method of filling a plug according to claim 20, wherein saidmalleable conductive layer is deposited by forming a liner of malleableconductive material in said opening.
 24. A method of filling a plugcomprising: forming a dielectric layer; forming an opening through saiddielectric layer; depositing a malleable conductive layer over a surfaceof said dielectric layer such that said malleable conductive layerenters said opening, said malleable conductive layer within said openingbeing insufficient in quantity to plug said opening; and, performing achemical mechanical polishing operation such that at least a portion ofsaid malleable conductive layer moves from said surface into saidopening to plug said opening.
 25. A method of filling a plug accordingto claim 24, wherein said chemical mechanical polishing operation isperformed with a slurry comprised of an alumina abrasive at neutral toslightly basic pH, and free of an oxidizer.
 26. A method of filling aplug according to claim 25, wherein said chemical mechanical polishingoperation is performed with a slurry mixture comprised of said slurryand a diluting solution mixed at a ratio of ten parts of said dilutingsolution to one part of said slurry.
 27. A method of filling a plugaccording to claim 24, wherein said malleable conductive layer isdeposited by forming a liner of malleable conductive material in saidopening.
 28. A method of filling a plug comprising: forming a dielectriclayer; forming an opening in said dielectric layer; depositing amalleable conductive layer in said opening, said malleable conductivelayer insufficient in quantity to fill said opening and said malleableconductive layer sufficient in quantity to form a liner of malleableconductive material in said opening; and, smearing said malleableconductive layer such that said malleable conductive layer plugs saidopening using a chemical mechanical polish and wherein said chemicalmechanical polishing operation is performed with a slurry free fromhydrogen peroxide, free from an oxidizer, and comprising an aluminaabrasive at neutral to slightly basic pH.
 29. A method of forminginterconnects comprising: forming a first dielectric layer; formingthrough holes in said first dielectric layer; filling said through holeswith a first conductive material; forming a second dielectric layer oversaid first dielectric layer; forming through holes in said seconddielectric layer, said through holes in said second dielectric layersubstantially vertically aligning with associated ones of said throughholes in said first dielectric layer; depositing a malleable conductivelayer over said second dielectric layer such that said malleableconductive layer enters each of said through holes, said malleableconductive layer within each of said through holes being insufficient inquantity to fill said through holes; and, smearing said malleableconductive layer such that said through holes in said second dielectriclayer are at least substantially filled.
 30. A method of forminginterconnects according to claim 29, wherein said first conductivematerial comprises a tungsten-based material.
 31. A method of forminginterconnects according to claim 29, wherein said malleable conductivelayer is smeared by polishing said malleable conductive layer such thatsaid through holes are at least substantially plugged.
 32. A method offorming interconnects according to claim 31, wherein said malleableconductive layer is polished using a slurry mixture comprised of aslurry, said slurry comprising an alumina abrasive and a neutral toslightly basic pH, wherein said slurry is free of an oxidizer.
 33. Amethod of forming interconnects according to claim 32, wherein saidslurry mixture further comprises a diluting solution mixed 10 parts ofsaid diluting solution to one part of said slurry.
 34. A method offorming interconnects according to claim 29 wherein said malleableconductive layer comprises a silver-based conductive material.
 35. Amethod of chemically-mechanically polishing a substrate to forminterconnects comprising: positioning said substrate against a polishinghead of a chemical mechanical polishing apparatus, said substrate havinga dielectric layer with vias formed therein and a malleable conductivelayer deposited over said dielectric layer so as to form a liner withineach of said vias; supplying a slurry mixture to a polishing pad of saidchemical mechanical polishing apparatus, said slurry mixture, and,polishing said substrate with said polishing pad and said slurry mixturesuch that said malleable conductive layer is smeared into said vias atleast substantially filling said vias.
 36. A method ofchemically-mechanically polishing a substrate to form interconnectsaccording to claim 35, wherein said substrate is polished by applying adown force on said substrate, said down force being sufficient to allowsaid vias to fill in tact.
 37. A method of chemically-mechanicallypolishing a substrate to form silver-based conductive metalinterconnects according to claim 35, wherein said slurry mixture issupplied as a slurry comprised of an alumina abrasive at slightlyneutral to basic pH, said slurry being free of an oxidizer.
 38. A methodof chemically-mechanically polishing a substrate to form silver-basedconductive metal interconnects according to claim 37, wherein saidslurry mixture further comprises a diluting solution, said dilutingsolution mixed ten parts of said diluting solution to one part of saidslurry.
 39. A method of forming a silver-based conductive material plugcomprising: forming a silicon nitride layer; forming an opening throughsaid silicon nitride layer; depositing a layer of silver-basedconductive material over a surface of said silicon nitride layer suchthat said layer of silver-based conductive material enters said opening,said layer of silver-based conductive material within said opening beinginsufficient in quantity to plug said opening; and, smearing said layerof silver-based conductive material across said surface of saiddielectric layer such that at least a portion of said layer ofsilver-based conductive material moves from said surface into saidopening to plug said opening.
 40. A method of forming interconnectscomprising: forming a first silicon nitride layer; forming through holesin said first silicon nitride layer; filling said through holes with atungsten-based conductive material; forming a second silicon nitridelayer over said first silicon nitride layer; forming through holes insaid second silicon nitride layer, at least one of said through holes insaid second silicon nitride layer substantially vertically aligning withan associated one of said through holes in said silicon nitride layer;forming a layer of a silver-based conductive material over said secondsilicon nitride layer such that said silver-based conductive materiallines said through holes such that said through holes in said secondsilicon nitride layer are less than filled by said silver-basedconductive material; and, smearing said silver-based conductive materialsuch that said through holes in said second silicon nitride layer are atleast substantially filled.
 41. A method of forming a ProgrammableConductor RAM cell comprising: forming a dielectric layer; forming anopening through said dielectric layer; depositing a malleable conductivelayer over a surface of said dielectric layer such that said malleableconductive layer enters said opening, said malleable conductive layerwithin said opening being insufficient in quantity to plug said opening;smearing said malleable conductive layer such that at least a portion ofsaid malleable conductive layer plugs said opening; etching back aportion of said malleable conductive layer within said opening;depositing a chalcogenide over said dielectric layer sufficient to fillsaid opening; polishing said device to remove portions of saidchalcogenide not within said opening; and, doping said chalcogenide withsaid malleable conductive layer.
 42. A method of forming a ProgrammableConductor RAM cell comprising: forming a first dielectric layer; formingthrough holes in said first dielectric layer; filling said through holeswith a first conductive material; forming a second dielectric layer oversaid first dielectric layer; forming through holes in said seconddielectric layer, said through holes in said second dielectric layersubstantially vertically aligning with associated ones of said throughholes in said first dielectric layer; depositing a silver-basedconductive material over said second dielectric layer such that saidsilver-based conductive material enters each of said through holes, saidsilver-based conductive material within each of said through holes beinginsufficient in quantity to fill said through holes; smearing saidsilver-based conductive material such that said through holes in saidsecond dielectric layer are at least substantially filled; etching backa portion of said silver-based conductive material within said openings;depositing a chalcogenide over said second dielectric layer sufficientto fill said openings; polishing said device to remove portions of saidchalcogenide not within said openings; and, doping said chalcogenidewith said silver-based conductive material.
 43. A method of forming aProgrammable Conductor RAM cell according to claim 44, wherein saidfirst conductive layer comprises a tungsten based material.
 44. A methodof forming a Programmable Conductor RAM cell comprising: forming a firstdielectric layer; forming through holes in said first dielectric layer;filling said through holes with a first conductive material; forming asecond dielectric layer over said first dielectric layer; formingthrough holes in said second dielectric layer, said through holes insaid second dielectric layer substantially vertically aligning withassociated ones of said through holes in said first dielectric layer;depositing a silver-based conductive material over said seconddielectric layer such that said silver-based conductive material enterseach of said through holes, said silver-based conductive material withineach of said through holes being insufficient in quantity to fill saidthrough holes; smearing said silver-based conductive material such thatsaid through holes in said second dielectric layer are at leastsubstantially filled; etching back a portion of said silver-basedconductive material within said openings; depositing a combination ofselenium and germanium over said second dielectric layer sufficient tofill said openings; polishing said device to remove portions of saidcombination of selenium and germanium not within said openings; and,doping said combination of selenium and germanium with said silver-basedconductive material.